Routing rules are defined in your application/config/routes.php file.
In it you’ll see an array called $route that permits you to specify
your own routing criteria. Routes can either be specified using wildcards
or Regular Expressions.

In a route, the array key contains the URI to be matched, while the
array value contains the destination it should be re-routed to. In the
above example, if the literal word “product” is found in the first
segment of the URL, and a number is found in the second segment, the
“catalog” class and the “product_lookup” method are instead used.

You can match literal values or you can use two wildcard types:

(:num) will match a segment containing only numbers.
(:any) will match a segment containing any character (except for ‘/’, which is the segment delimiter).

Note

Wildcards are actually aliases for regular expressions, with
:any being translated to [^/]+ and :num to [0-9]+,
respectively.

Note

Routes will run in the order they are defined. Higher routes
will always take precedence over lower ones.

Note

Route rules are not filters! Setting a rule of e.g.
‘foo/bar/(:num)’ will not prevent controller Foo and method
bar to be called with a non-numeric value if that is a valid
route.

If you prefer you can use regular expressions to define your routing
rules. Any valid regular expression is allowed, as are back-references.

Note

If you use back-references you must use the dollar syntax
rather than the double backslash syntax.

A typical RegEx route might look something like this:

$route['products/([a-z]+)/(\d+)']='$1/id_$2';

In the above example, a URI similar to products/shirts/123 would instead
call the “shirts” controller class and the “id_123” method.

With regular expressions, you can also catch multiple segments at once.
For example, if a user accesses a password protected area of your web
application and you wish to be able to redirect them back to the same
page after they log in, you may find this example useful:

$route['login/(.+)']='auth/login/$1';

Note

In the above example, if the $1 placeholder contains a
slash, it will still be split into multiple parameters when
passed to Auth::login().

For those of you who don’t know regular expressions and want to learn
more about them, regular-expressions.info
might be a good starting point.

It is possible to use HTTP verbs (request method) to define your routing rules.
This is particularly useful when building RESTful applications. You can use standard HTTP
verbs (GET, PUT, POST, DELETE, PATCH) or a custom one such (e.g. PURGE). HTTP verb rules
are case-insensitive. All you need to do is to add the verb as an array key to your route.
Example:

$route['products']['put']='product/insert';

In the above example, a PUT request to URI “products” would call the Product::insert()
controller method.

$route['products/(:num)']['DELETE']='product/delete/$1';

A DELETE request to URL with “products” as first the segment and a number in the second will be
mapped to the Product::delete() method, passing the numeric value as the first parameter.

This route points to the action that should be executed if the URI contains
no data, which will be the case when people load your root URL.
The setting accepts a controller/method value and index() would be
the default method if you don’t specify one. In the above example, it is
Welcome::index() that would be called.

Note

You can NOT use a directory as a part of this setting!

You are encouraged to always have a default route as otherwise a 404 page
will appear by default.

$route['404_override']='';

This route indicates which controller class should be loaded if the
requested controller is not found. It will override the default 404
error page. Same per-directory rules as with ‘default_controller’
apply here as well.

It won’t affect to the show_404() function, which will
continue loading the default error_404.php file at
application/views/errors/error_404.php.

$route['translate_uri_dashes']=FALSE;

As evident by the boolean value, this is not exactly a route. This
option enables you to automatically replace dashes (‘-‘) with
underscores in the controller and method URI segments, thus saving you
additional route entries if you need to do that.
This is required, because the dash isn’t a valid class or method name
character and would cause a fatal error if you try to use it.

Important

The reserved routes must come before any wildcard or
regular expression routes.